Safety device for valve gear of expansible chamber motors



July 8, 1947. J. NAAB ETAL SAFETY DEVICE FOR VALVE GEAR OF EXPANSIBLECHAMBER MOTORS Filed Oct. 16, 1945 7 INVENTORS THE R ATTORN EY- PatentedJuly 8, 1947 SAFETY DEVICE FOR VALVE GEAR OF EXPANSIBLE CHAll/IBER-MOTORS Julius Naab and Richard Ostwald, Easton, Pa., assignors toIngersoll-Rand Company, New York, N. Y., a corporation of New JerseyApplication October 16, 1945, Serial No. 622,596

3 Claims.

This invention relates to safety devices, and more particularly to asafety device for a pressure fluid actuated engine of the reciprocatorypiston type.

One object of the invention is to prevent the operation of the engine atunsafe speeds.

A more specific object is to prevent the distribution of pressure fluidto the piston chamber whenever the speed of the engine exceeds a certainpredetermined rate.

Other objects will be in part obvious and in part pointed outhereinafter.

In the drawings accompanying this specification and in which similarreference numerals refer to similar parts,

Figure l is a longitudinal side elevation of an engine equipped with asafety device constructed in accordance with the practice of theinvention.

Figure 2 is an enlarged plan view, partly broken away, taken throughFigure 1 on the line 2-2 looking in the direction indicated by thearrows, and

Figure 3 is a longitudinal view, partly in section, taken through Figure2 on the line 3-3 looking in the direction indicated by the arrows.

Referring more particularly to the drawings, the invention isshownapplied to a horizontal engine 20 having the usual bed plate 2| and acrank shaft 22 therein carrying a fly wheel 23. On one end of the bedplate is a distance piece 24 to support a cylinder 25 having a pistonchamber 26 to accommodate a reciprocatory piston 21 the rod 28 of whichmay be operatively connected in any Well known manner, to the crankshaft 22.

At the side of the cylinder 25 is a steam chest 29 fcontaining a bushing30 the interior of which constitutes a valve chamber 3| and communicateswith the front and rear ends of the piston chamber 26 through passages32 and 33, respectively. The intermediate portion of the steam chest isrecessed to provide a supply chamber 34 that communicates with theintermediate portion of the valve chamber 3| through ports 35 in thebushing 30, and the admission of steam into the chamber 34 is controlledby a hand-operated throttle valve 36 on top of the steam chest andcommunicating with the chamber 34 through a passage 31.

The steam chest is further recessed to provide exhaust chambers 38 and39 at the front and rear ends, respectively, of the valve chamber, andsaid exhaust chambers may be connected by a passage (not shown) havingan exhaust outlet 40.

The ports 4| and 42 through which the passages 32 and 33, respectively,communicate with the valve chamber 3| are located at suitably spaceddistances from the ends of the valve chamber and are controlled by theheads 43 and 44 of a valve 45 reciprocable in the valve chamber. Theheads 43 and 44 are connected by a stem 45 and are of the same diameterso that their opposed inner surfaces 41 will be of equal area and thesteam acting constantly tl1ereagainst will be ineffective to shift thevalve.

The linkage serving to impart reciprocatory motion to the valve 45 isconnected to the crank shaft 22. It comprises a rod 48 that extendsaxially from the head 43 of the valve and slidably through a cover plate49, at the adjacent end or the valve chest 29, and through an end of abracket 53 spaced from and joined to the cover plate 49 by webs 51. Theintermediate portion 52 of the rod 48 is threaded through an end of ayoke 53 which carries, near its opposite end, a guide bar 54 arranged inparallelism with the rod 48. One end of the bar 54 is slidable in a bore55 in the bracket 55] and its opposite end 56 is slidable in a bushing57 arranged within a cylindrical enlargement 58 at the edge of the plate49. On the end of the yoke, adjacent the bar 54, is an axle 53 thatextends transversely through an end of an arm '60, and a washer 6|overlying the end of the axle and secured thereto by a screw 62 retainsthe arm 69 on the axle.

The arm 50 has a free running fit on the axle 59. Its opposite end ishollow, having a bore 83 to receive an end of a rod 64 the opposite endof which is mounted, for pivotal movement, upon a pin 65 positionedeccentrically on the end of the crank shaft 22. The rod (54 has a slidefit in the bore 63 and is connected to the arm 69 by a pin 6% whichextends through the rod 64 and through the opposed sides of the arm andis so proportioned, for strength, that it will safely withstand thestrains to which it is subjected for normally driving the valve 45 butwill break when subjected to abnormal strains.

The means provided for causing such breaking of the pin 36 is actuatedby the linkage which drives the valve 45 and is preferably arranged, asshown, on the end 55 of the guide bar 54. It comprises a rod 67 that isthreadedly connected to the end 56 of the bar .54, to extend axiallythereof, and at an intermediate portion of the rod fil' is a cylindricalenlargement 58 to act as a stop member for a weight 69 encircling therod 61 between the enlargement 68 and the bar 54.

The weight 69 has a sliding fit in the bushing 57 and on the rod 6! andis of less length than the distance between the enlargement 68 and theend of the bar 54 to permit of a limited degree of endwise movement onthe rod 61. Near the inner end of the weight is an external annu largroove to accommodate an expansion ring H which is normally retainedentirely within the groove 10 by the bushing 51 but will expand to liepartly within the groove 10 and partly over the end surface of thebushing 51 when the weight occupies its outermost limiting position inabutment with the enlargement 58.

Normally, however, the weight 69' abuts the end 56 of the bar 54 and isheld in this position by a spring 72 encircling the rod 6'! and seatingagainst the outer end of the weight. The opposite end of the springengages a spring seat 13 slidable upon the rod 61, and a nut 14 isthreaded on the rod ill, against the seat 73, to Vary the force of thespring 12.

Preferably a cup-like casing '15 is disposed telescopically upon the endof the enlargement 58 to protect the rod 67 and the associated partsfrom exposure to dust and dirt.

During the operation 'of the engine at normal speed, and with the spring'12 correctly adjusted to hold the weight 69 against the bar 54, theweight will reciprocate with the valve 45, and its range of movementwill be of only such extent that the expansion ring II will not passbeyond the end of the bushing 51 but will remain contracted within thegroove 10.

In the event that the engine speed rises to an excessive rate, as whenthe governing apparatus serving to control the speed of the engine failsto function properly, the consequent accelerating speed will cause theweight 69 to be projected relatively to the bar 54 against theenlargement 68. This movement of the weight will cam the expansion ringH out of the bushing 51 and the ring will then expand and engage the endsurface of the bushing 51, thereby forming an interlocking connectionbetween the bar 54 and the casing of the engine. The followingretractive stroke of the rod 64 will cause the pin 66 to be sheared offat the cooperating surfaces of the rod 64 and the arm 60. In this waythe driving connection between the crank shaft 22' and the valve 45 willbe broken.

The valve will then remain stationary in its rearmost limiting positionto valve pressurefluid into the rearward end of the piston chamber 25for holding the piston immovable.

We claim:

1. A safety device for a pressure fluid actuated engine, comp-rising acasing having a piston chamber and supply passages leading to the endsof the piston chamber, a reciprocatory valve to control the supplypassages, a driver, linkage to transmit motion from the driver to thevalve having in its organization a connector adapted to break whensubjected to an abnormal strain for detaching the driver from the valve,and means reciprocable with the valve and acting responsively to asuper-normal speed of the driver for interlockingly engaging the casingto cause the breaking of the connector. w W

2. A safety device for a pressure fluid actuated engine, comprising acasing having a piston chamber and supply passages leading to the endsof the piston chamber, a reciprocatory valve to control the supplypasasges, a driver, linkage to transmit motion from the driver to thevalve having in its organization a pair of members and a connectortherefor adapted to break when subjected to an abnormal strain fordetaching the driver from the valve, a weight actuated by the linkage tonormally reciprocate at the rate of speed of the valve and beingprojected beyond its normal range of movement at a super-normal speed ofthe driver, and means carried by the weight acting to hold one memberstationary and thereby enable the other member to break the connectorwhenever the weight is projected beyond its normal range of movement.

3. A safety device for a pressure fluid actuated engine, comprising acasing having a piston chamber and supply passages leading to the endsof the piston chamber, a riciprocatory valve to control the supplypasages, a driver, linkage to transmit motion from the driver to thevalve having in its organization a pair of members and a connectortherefor adapted to break when subjected to an abnormal strain fordetaching the driver from the valve, a spring-pressed weight actuated bythe linkage to normally reciprocate at the rate of speed of the valveand being projected beyond its normal range of movement at a supernonnalspeed or. the driver, a guide for the weight, and an expansion ring inthe periphery of the weight to eiiect an interlocking connection betweenthe weight and the guide upon projectile motion of the Weight forholding one member stationary and thereby enable the other member tobreak the connector.

JULIUS NAAB. RICHARD OSTWALD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 689,784 Bradbury et a1. Dec. 24,1901 989,062 Sargent Apr. 11, 1911 1,363,067 TWa Dec. 21, 1920

